Zoysia grass, known for its dense growth and resilience, can become an unwelcome guest when it invades flowerbeds, gardens, or even other parts of your lawn. Its aggressive spreading nature can quickly make it a nuisance, leading homeowners to seek effective methods for eradication. While cultural practices can help, sometimes a chemical solution becomes necessary. Choosing the “best” chemical isn’t straightforward; it depends on various factors, including the extent of the infestation, the surrounding vegetation, and your long-term landscaping goals. This comprehensive guide explores the most effective chemical options for killing Zoysia grass, their pros and cons, and essential safety considerations.
Understanding Zoysia Grass and Why It’s Difficult to Eradicate
Zoysia grass is a warm-season perennial grass prized for its ability to create a thick, luxurious lawn that can withstand heavy foot traffic. Its dense growth habit crowds out weeds, and its tolerance to heat and drought makes it a popular choice in many regions. However, these same characteristics also make it challenging to eliminate when it’s growing where it shouldn’t be.
One of the primary reasons Zoysia grass is so difficult to kill is its extensive root system. This root system, composed of rhizomes and stolons, allows the grass to spread rapidly and store significant energy reserves. Even if the above-ground portion of the plant is killed, the underground roots can quickly regenerate new growth. This regrowth from the roots necessitates a systemic herbicide that can effectively target and kill the entire plant, root system included.
Another challenge is the grass’s dormancy period. During colder months, Zoysia grass turns brown and appears dead. However, it’s merely dormant, waiting for warmer temperatures to resume growth. Applying herbicides during dormancy may not be effective, as the plant’s metabolism slows down, reducing its ability to absorb and translocate the chemical.
Identifying the Right Chemical Solution
Choosing the right chemical solution for Zoysia grass eradication requires careful consideration. There are two main categories of herbicides: selective and non-selective. Selective herbicides are designed to kill specific types of plants while leaving others unharmed. Non-selective herbicides, on the other hand, kill all vegetation they come into contact with.
Non-Selective Herbicides: Glyphosate and its Alternatives
Glyphosate, the active ingredient in Roundup and other similar products, is a widely used non-selective herbicide. It works by inhibiting an enzyme essential for plant growth. Because it’s non-selective, glyphosate will kill any plant it comes into contact with, making it crucial to protect desirable vegetation during application.
The effectiveness of glyphosate on Zoysia grass stems from its systemic action. After application to the foliage, the herbicide is absorbed and translocated throughout the plant, including the roots. This ensures that the entire plant, not just the above-ground portion, is killed. Multiple applications may be necessary, especially for established Zoysia grass infestations.
However, glyphosate has faced increasing scrutiny due to concerns about its potential health and environmental impacts. While the scientific community is still debating these issues, some homeowners prefer to explore alternative non-selective herbicides.
Alternatives to glyphosate include products containing glufosinate. Glufosinate is also a non-selective herbicide, but it works differently than glyphosate. It inhibits a different enzyme involved in plant metabolism. While glufosinate is effective, it may require more frequent applications than glyphosate, and it is a contact herbicide which means complete coverage is crucial.
Another option is to use a combination of herbicides. Some products combine glyphosate with other active ingredients to enhance their effectiveness. Always read and follow the label instructions carefully when using any herbicide mixture.
Selective Herbicides: A More Targeted Approach?
While non-selective herbicides like glyphosate are effective for killing Zoysia grass, they pose a risk to surrounding desirable plants. This is where selective herbicides come into play. Selective herbicides are designed to target specific types of plants while leaving others unharmed.
Unfortunately, there are very few selective herbicides specifically labeled for killing Zoysia grass without harming other common lawn grasses like fescue, Kentucky bluegrass, or perennial ryegrass. This is because Zoysia grass is closely related to other turfgrasses, making it difficult to find a chemical that can selectively target it.
Some herbicides containing active ingredients like sulfosulfuron or trifloxysulfuron may offer some suppression of Zoysia grass. However, these products are typically used for weed control in other turfgrass species and may not completely eliminate Zoysia grass. Furthermore, they can cause temporary discoloration or thinning of the Zoysia grass before it eventually dies.
The success of selective herbicides depends on several factors, including the specific product used, the timing of application, and the overall health of the Zoysia grass. Multiple applications may be necessary, and it’s essential to follow the label instructions carefully to avoid damaging desirable plants.
Choosing the Right Herbicide for Your Situation
The “best” herbicide for killing Zoysia grass depends on your specific circumstances. If you need to eliminate Zoysia grass from a flowerbed or garden, a non-selective herbicide like glyphosate is likely the most effective option. However, you must take precautions to protect surrounding plants by carefully applying the herbicide directly to the Zoysia grass, using a shield, or painting it on.
If you’re trying to remove Zoysia grass from your lawn, the situation is more complex. Because of the lack of truly selective herbicides, you may need to resort to spot-treating with a non-selective herbicide. This requires patience and precision to avoid killing the desirable grasses around the Zoysia grass. Repeated applications will likely be necessary to eradicate the Zoysia grass completely.
Another approach is to kill the entire area containing the Zoysia grass and then reseed or sod with your desired turfgrass species. This may seem drastic, but it can be the most effective way to achieve a uniform lawn.
Proper Application Techniques for Maximum Effectiveness
Regardless of the herbicide you choose, proper application techniques are crucial for maximizing effectiveness and minimizing potential harm to the environment and surrounding vegetation.
Timing is Key
The timing of herbicide application significantly impacts its effectiveness. As mentioned earlier, applying herbicides during the Zoysia grass’s dormancy period is generally ineffective. The best time to apply herbicides is during the active growing season when the grass is actively absorbing nutrients and water. This allows the herbicide to be translocated throughout the plant more effectively.
The ideal time to apply herbicides is when the Zoysia grass is actively growing but not under stress from heat or drought. Early morning or late evening applications are generally preferred, as temperatures are cooler, and there’s less wind to drift the herbicide onto desirable plants.
Preparation and Safety Precautions
Before applying any herbicide, carefully read and understand the label instructions. The label contains important information about the product’s application rate, safety precautions, and environmental hazards.
Always wear appropriate personal protective equipment (PPE) when handling herbicides, including gloves, long sleeves, long pants, and eye protection. A respirator may also be necessary, depending on the specific product and application method.
Mix the herbicide according to the label instructions, using the recommended amount of water. Avoid mixing more herbicide than you need, as this can lead to disposal problems.
Application Methods
The application method depends on the size and location of the Zoysia grass infestation. For small areas, a handheld sprayer is often sufficient. For larger areas, a backpack sprayer or a tank sprayer attached to a lawn tractor may be more efficient.
When applying the herbicide, ensure thorough coverage of the Zoysia grass foliage. Avoid spraying to the point of runoff, as this can waste herbicide and increase the risk of environmental contamination.
For spot treatments, use a shield to protect surrounding plants from accidental overspray. You can also use a paintbrush or sponge to apply the herbicide directly to the Zoysia grass foliage.
Post-Application Care
After applying the herbicide, avoid mowing or watering the treated area for at least 24 hours, or as specified on the label. This allows the herbicide to be absorbed and translocated throughout the plant.
Monitor the treated area for signs of Zoysia grass regrowth. Repeat applications may be necessary to completely eradicate the grass.
Alternative Methods for Zoysia Grass Control
While chemical herbicides can be effective for killing Zoysia grass, they are not the only option. Alternative methods, such as cultural practices and manual removal, can also be effective, especially for small infestations.
Cultural Practices
Cultural practices involve modifying the growing conditions to favor the desired plants and discourage the growth of Zoysia grass. These practices include proper watering, fertilization, and mowing.
Proper watering is essential for maintaining a healthy lawn. Water deeply and infrequently, rather than shallowly and frequently. This encourages deep root growth in the desired grasses, making them more competitive against Zoysia grass.
Fertilizing your lawn properly can also help to promote healthy growth and make it more resistant to Zoysia grass invasion. Use a fertilizer that is specifically formulated for your desired turfgrass species and follow the label instructions carefully.
Mowing at the correct height can also help to control Zoysia grass. Mowing too low can stress the desired grasses and make them more susceptible to Zoysia grass invasion.
Manual Removal
For small infestations, manual removal can be an effective way to eliminate Zoysia grass. This involves digging up the grass and its root system.
To manually remove Zoysia grass, use a shovel or garden fork to loosen the soil around the grass. Then, carefully lift the grass and its root system out of the ground. Be sure to remove all of the roots, as any remaining roots can regenerate new growth.
After removing the Zoysia grass, fill the hole with soil and reseed or sod with your desired turfgrass species.
Long-Term Management and Prevention
Once you’ve successfully eradicated Zoysia grass from your lawn or garden, it’s essential to take steps to prevent it from returning. This involves maintaining a healthy lawn or garden and being vigilant about removing any new Zoysia grass growth.
- Regularly inspect your lawn or garden for signs of Zoysia grass. If you see any new growth, remove it immediately.
- Maintain a healthy lawn or garden by following proper watering, fertilization, and mowing practices.
- Consider using a pre-emergent herbicide to prevent Zoysia grass seeds from germinating.
By following these tips, you can keep your lawn or garden free of Zoysia grass and enjoy a beautiful, healthy landscape.
Understanding Herbicide Resistance
The repeated use of the same herbicide can lead to herbicide resistance in Zoysia grass populations. This means that the herbicide becomes less effective over time, as the Zoysia grass develops mechanisms to tolerate or detoxify the chemical.
To prevent herbicide resistance, it’s important to rotate herbicides with different modes of action. This means using herbicides that kill plants in different ways. You can also use a combination of herbicides with different modes of action.
Another strategy for preventing herbicide resistance is to use integrated pest management (IPM) practices. IPM involves using a variety of control methods, including cultural practices, manual removal, and biological control, in addition to herbicides. This reduces the reliance on herbicides and helps to prevent the development of resistance.
Conclusion: A Multifaceted Approach
Killing Zoysia grass requires a multifaceted approach that considers the specific situation, the desired outcome, and the potential risks associated with each control method. While chemical herbicides, particularly non-selective options like glyphosate, can be effective, they should be used judiciously and with careful attention to safety and environmental concerns. Alternative methods, such as cultural practices and manual removal, can also play a valuable role in Zoysia grass control, especially for small infestations. By understanding the challenges of Zoysia grass eradication and employing a combination of control strategies, homeowners can effectively manage this persistent plant and maintain a healthy, beautiful landscape. Remember that patience and persistence are key to long-term success.
What are the most effective herbicides for killing Zoysia grass selectively in cool-season lawns?
For selectively removing Zoysia from cool-season grasses like fescue, ryegrass, and Kentucky bluegrass, herbicides containing glyphosate are generally too non-selective and will damage or kill desirable grasses alongside the Zoysia. The best approach involves using herbicides specifically formulated for broadleaf weed control that are also safe for cool-season grasses. Products containing active ingredients like quinclorac, triclopyr, and dicamba, when used at the correct rates and according to the label, can effectively weaken and eventually kill Zoysia without severely impacting the surrounding cool-season turf.
However, complete eradication often requires multiple applications over several weeks or months, especially for well-established Zoysia patches. Always read and follow the product label instructions carefully, paying close attention to application rates, weather conditions, and any specific precautions for your lawn type. Consider spot treatments to minimize potential harm to the surrounding desirable grasses. Furthermore, monitor the treated areas closely and reapply as needed, following label instructions regarding minimum intervals between applications.
Can I use vinegar or other homemade remedies to kill Zoysia grass?
While household vinegar, particularly horticultural vinegar with a higher acetic acid concentration (20-30%), can act as a contact herbicide, it’s generally not an effective solution for completely eradicating Zoysia grass. Vinegar can burn the foliage of the Zoysia, causing it to temporarily brown and appear damaged, but it typically doesn’t kill the roots. This means the Zoysia will likely regrow from its rhizomes and stolons, leading to only a short-term cosmetic improvement.
Furthermore, vinegar is non-selective and will damage or kill any vegetation it comes into contact with, including desirable grasses and plants. Homemade remedies like vinegar also lack the systemic action of commercial herbicides, which are absorbed by the plant and transported to the roots for more effective control. Repeated applications of vinegar might eventually weaken the Zoysia, but this is a time-consuming process with uncertain results and can also negatively impact soil pH over time.
Is it possible to kill Zoysia grass without harming the desirable grass around it?
Killing Zoysia grass without harming surrounding desirable grasses is challenging but achievable, particularly with careful application and the correct herbicide choice. The key lies in understanding the selectivity of herbicides and using a product that targets Zoysia more effectively than the desired turfgrass. Spot treatments, rather than blanket applications, are crucial for minimizing the impact on surrounding grass. Furthermore, meticulous application using a handheld sprayer helps ensure the herbicide is applied only to the Zoysia.
Proper watering and fertilization of the desired grass can also enhance its resilience and ability to recover from any potential minor damage caused by the herbicide. In some cases, it might be necessary to overseed the treated areas with desirable grass seed after the Zoysia has been effectively controlled to fill in any bare spots. It’s also vital to consider the specific type of desirable grass you have, as some are more sensitive to certain herbicides than others. Always consult the product label for specific recommendations and precautions related to your lawn type.
What is the best time of year to apply herbicide to kill Zoysia grass?
The optimal time to apply herbicide for Zoysia grass control depends on several factors, including the specific herbicide being used and the desired outcome. Generally, post-emergent herbicides are most effective when Zoysia is actively growing, typically during the warmer months of late spring and early summer. This is when the plant is actively transporting nutrients and herbicides throughout its system, maximizing the chances of killing the roots.
However, avoid applying herbicides during periods of extreme heat or drought stress, as this can reduce their effectiveness and potentially harm desirable grasses. In some cases, a second application might be necessary in the late summer or early fall to control any regrowth from rhizomes or stolons. Always consult the product label for specific recommendations on the optimal timing and frequency of applications for the particular herbicide you are using. Consideration should also be given to local weather patterns and the overall health of the Zoysia grass.
How long does it take to completely kill Zoysia grass after applying herbicide?
The time it takes to completely kill Zoysia grass after applying herbicide varies depending on several factors, including the type of herbicide used, the size and density of the Zoysia patch, environmental conditions, and the overall health of the Zoysia. With effective herbicides like glyphosate (for non-selective control) or selective herbicides applied appropriately, visible signs of damage, such as yellowing or browning of the foliage, might appear within a week or two.
However, complete eradication, including killing the roots and preventing regrowth, can take several weeks or even months, especially for well-established Zoysia patches. Multiple applications might be necessary to achieve complete control, following the recommended intervals on the product label. Factors like rainfall, soil type, and temperature can also influence the herbicide’s effectiveness and the time it takes to kill the Zoysia. Regular monitoring of the treated area is crucial to assess progress and determine if additional treatments are needed.
What are the potential risks associated with using herbicides to kill Zoysia grass?
Using herbicides to kill Zoysia grass carries potential risks, both to the environment and to desirable plants. The most significant risk is non-target damage, where the herbicide unintentionally harms or kills surrounding desirable grasses, flowers, shrubs, or trees. This is particularly likely with non-selective herbicides like glyphosate, which kill virtually any plant they come into contact with. Even selective herbicides can cause temporary discoloration or stunting of growth in desirable grasses if applied incorrectly or at excessively high rates.
Environmental risks include potential contamination of soil and water resources, particularly if herbicides are over-applied or used near waterways. Some herbicides can also pose a threat to beneficial insects and wildlife. To minimize these risks, always read and follow the product label instructions carefully, use appropriate personal protective equipment, and apply herbicides only when necessary and in targeted areas. Consider alternative methods of Zoysia control, such as manual removal or cultural practices, before resorting to herbicides.
What are some alternatives to using chemical herbicides to control Zoysia grass?
Several alternatives to chemical herbicides exist for controlling Zoysia grass, though they often require more labor and patience. Manual removal, such as digging up individual clumps of Zoysia, can be effective for small infestations, especially if done diligently to remove all rhizomes and stolons. Smothering the Zoysia with a non-permeable material like cardboard or black plastic can also kill it by depriving it of sunlight, but this method can take several weeks or months and will also kill any desirable vegetation underneath.
Cultural practices can also help suppress Zoysia and promote the growth of desirable grasses. These include proper watering, fertilization, and mowing practices that favor the desired turfgrass species. Aerating the soil can also improve drainage and reduce soil compaction, making it more difficult for Zoysia to thrive. Over-seeding with a dense stand of desirable grass can also help compete with Zoysia and prevent it from spreading. Combining these methods can often provide effective long-term control without the use of chemicals.